U.S. patent number 6,608,076 [Application Number 10/147,168] was granted by the patent office on 2003-08-19 for camptothecin derivatives and polymeric conjugates thereof.
This patent grant is currently assigned to Enzon, Inc.. Invention is credited to Richard B. Greenwald, Hong Zhao.
United States Patent |
6,608,076 |
Greenwald , et al. |
August 19, 2003 |
**Please see images for:
( Certificate of Correction ) ** |
Camptothecin derivatives and polymeric conjugates thereof
Abstract
Polymeric conjugates of camptothecin derivatives having
increased circulating half-lives are disclosed. In preferred
aspects, the E ring lactone of the camptothecin derivative is
opened and functionalized to allow attachment of a polymer such as
PEG in the 17- or 20-position thereof. A representative example of
such compounds is ##STR1## Methods of preparing and using the same
are also disclosed.
Inventors: |
Greenwald; Richard B.
(Somerset, NJ), Zhao; Hong (Edison, NJ) |
Assignee: |
Enzon, Inc. (Bridgewater,
NJ)
|
Family
ID: |
27733658 |
Appl.
No.: |
10/147,168 |
Filed: |
May 16, 2002 |
Current U.S.
Class: |
514/285; 514/283;
546/70; 546/47 |
Current CPC
Class: |
A61P
43/00 (20180101); A61K 47/55 (20170801); A61P
35/00 (20180101); C07D 471/14 (20130101); A61K
47/60 (20170801) |
Current International
Class: |
C07D
471/00 (20060101); C07D 471/14 (20060101); C07D
491/22 (20060101); C07D 491/00 (20060101); C07D
519/00 (20060101); A61K 031/474 (); C07D
471/12 () |
Field of
Search: |
;546/70,47
;514/285,283 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
4914205 |
April 1990 |
Sawada et al. |
6342506 |
January 2002 |
Giovanella et al. |
|
Foreign Patent Documents
Other References
John A. Adamovics and C. Richard Hutchinson Prodrug Analogues of
the Antitumor Alkaloid Camptothecin Journal of Medicinal Chemistry,
1979, vol. 22, No. 3, PP310-314. .
Hertzberg, et al. Modification of the Hydroxy Lactone Ring of
Camptothecin: Inhibition of Mammalian Topoisomerase I and
Biological Activity J. Med. Chem. 1989, 32, 715-720. .
Yaegashi, et al. Synthesis and Antitumor Activity of
20(S)-Camptothecin Derivatives. A-Ring-Substituted
7-Ethylcamptothecins and Their E-Ring-Modified Water-Soluble
Derivatives Chem. Pharm. Bull. 42(12) 2518-2525 (1994) vol. 42, No.
12. .
Sawada et al. Chemical Modification of an Antitumor Alkaloid,
20(S)-Camptothecin: E-Lactone Ring-Modified Water-Soluble
Derivatives of 7-Ethylcamptothecin Chem. Pharm. Bull. 41(2) 310-313
(1993) vol. 41, No. 2..
|
Primary Examiner: Aulakh; C. S.
Attorney, Agent or Firm: Muserlian, Lucas & Mercanti,
LLP
Claims
We claim:
1. A compound comprising Formula I: ##STR19##
wherein: R.sub.1 is selected from the group consisting of amino
acid residues, peptide residues containing from about 2 to about 10
amino acids, Y.sub.3 --(L.sub.2).sub.p --A.sub.2 and R.sub.2 ;
Y.sub.3 is O, S or N.sub.3 ; p is zero or one; L.sub.2 is a
bifunctional linker; Y.sub.1 is O, S or NR.sub.7 ; Y.sub.2 is O, S,
CR.sub.5 R.sub.6 or NR.sub.7 ; L.sub.1 is a bifunctional linker; a
and b are independently zero or one; A.sub.1 and A.sub.2 are
independently selected from the group consisting of hydrogen, amino
protecting groups, NR.sub.8 R.sub.9, amino acid residues, peptide
residues containing from about 2 to about 10 amino acids; polymeric
residues, R.sub.10, SR.sub.11, NC(O)R.sub.12 ; D.sub.3 -D.sub.7 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyls, substituted
aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8 alkoxys, C.sub.1-8
hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys, gyrals, CO.sub.2
R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl, amino, SR.sub.15,
NR.sub.16 SR.sub.17 or OR.sub.18, where D.sub.4 and D.sub.5
optionally, when taken together, form a saturated 3-7 membered
heterocyclic ring which may contain O, S or NR.sub.19 groups, where
R.sub.19 is hydrogen or a C.sub.1-6 alkyl; D.sub.8 -D.sub.9 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyls, substituted
aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8 hydroxyalkyls;
D.sub.10 is H, and R.sub.2-18 are independently selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-19 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted alkyls,
C.sub.3-8 substituted cyloalkyls, aryls, substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy,
provided that at least one of A.sub.1 and A.sub.2 comprise a
polymeric residue.
2. The compound of claim 1, wherein Y.sub.1 and Y.sub.2 are each
O.
3. The compound of claim 1, wherein R.sub.2 -R.sub.14 and D.sub.3
-D.sub.9 are each hydrogen.
4. The compound of claim 1, wherein A.sub.1 is a polymer
residue.
5. The compound of claim 4, wherein said polymer residue further
includes a capping group J, selected from the group consisting of
OH, NH.sub.2, SH, CO.sub.2 H, C.sub.1-6 alkyl moieties and
##STR20##
6. A compound of claim 5, of the formula: ##STR21##
7. The compound of claim 1, wherein A.sub.2 is a polymer
residue.
8. The compound of claim 7, wherein said polymer residue further
includes a capping group J, selected from the group consisting of
OH, NH.sub.2, SH, CO.sub.2 H, C.sub.1-6 alkyl moieties and
##STR22##
9. A compound of claim 8, of the formula: ##STR23##
10. The compound of claim 1, wherein A.sub.1 comprises a
polyalkylene oxide residue.
11. The compound of claim 1, wherein A.sub.2 comprises a
polyalkylene oxide residue.
12. The compound of claim 1, wherein A.sub.1 comprises a
polyethylene glycol residue.
13. The compound of claim 1, wherein A.sub.2 comprises a
polyethylene glycol residue.
14. The compound of claim 6, wherein A.sub.1 comprises a
polyethylene glycol residue.
15. The compound of claim 9, wherein A.sub.2 comprises a
polyethylene glycol residue.
16. The compound of claim 12, wherein A.sub.1 is selected from the
group consisting of J--O--(CH.sub.2 CH.sub.2 O).sub.x --,
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 C(O)--O--,
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 NR.sub.20 --,
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
--O--C(O)CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, --NR.sub.20 CH.sub.2 CH.sub.2 --O--(CH.sub.2 CH.sub.2
O).sub.x --CH.sub.2 CH.sub.2 NR.sub.20 --, and --SHCH.sub.2
CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
wherein: x is the degree of polymerization; R.sub.20 is selected
from the group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.1-12
branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted
alkyls, C.sub.3-8 substituted cyloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy
and J is a capping group.
17. The compound of claim 13, wherein A.sub.2 is selected from the
group consisting of J--O--(CH.sub.2 CH.sub.2 O).sub.x,--
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 C(O)--O--,
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 NR.sub.21 --,
J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
--O--C(O)CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, --NR.sub.21 CH.sub.2 CH.sub.2 --O--(CH.sub.2 CH.sub.2
O).sub.x --CH.sub.2 CH.sub.2 NR.sub.21 --, and --SHCH.sub.2
CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
herein: x is the degree of polymerization; R.sub.21 is selected
from the group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12
branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted
alkyls, C.sub.3-8 substituted cyloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy
and J is a capping group.
18. The compound of claim 16, wherein A.sub.1 comprises
--O--(CH.sub.2 CH.sub.2 O).sub.x -- and x is a positive integer
selected so that the weight average molecular weight is at least
about 20,000 Da.
19. The compound of claim 17, wherein A.sub.2 comprises
--O--(CH.sub.2 CH.sub.20).sub.x -- and x is a positive integer
selected so that the weight average molecular weight thereof is at
least about 20,000 Da.
20. The compound of claim 16, wherein A.sub.1 has a weight average
molecular weight of from about 20,000 Da to about 100,000 Da.
21. The compound of claim 17, wherein A.sub.2 has a weight average
molecular weight of from about 20,000 Da to about 100,000 Da.
22. The compound of claim 16, wherein A.sub.1 has a weight average
molecular weight of from about 25,000 Da to about 60,000 Da.
23. The compound of claim 17, wherein A.sub.2 has a weight average
molecular weight of from about 25,000 Da to about 60,000 Da.
24. The compound of claim 1, wherein L.sub.1 is selected from the
group consisting of: (CH.sub.2).sub.n, (CH.sub.2).sub.3 NH--C(O)
(CH.sub.2).sub.3 NH-- --NH(CH.sub.2 CH.sub.2 O).sub.n
(CH.sub.2).sub.n NR.sub.22 --, --NH(CH.sub.2 CH.sub.2 O).sub.n --,
--NH(C.sub.23 R.sub.24).sub.n O--, --C(O)(CR.sub.23 R.sub.24).sub.n
NHC(O)(CR.sub.25 R.sub.26).sub.q NR.sub.27 --,
--C(O)O(CH.sub.2).sub.n O--, --C(O)(CR.sub.23 R.sub.24).sub.n
NR.sub.27 --, --C(O)NH(CH.sub.2 CH.sub.2 O).sub.n (CH.sub.2).sub.n
NR.sub.27 --, --C(O)O--(CH.sub.2 CH.sub.2 O).sub.n NR.sub.27 --,
--C(O)NH(CR.sub.23 R.sub.24).sub.n O--, --C(O)O(CR.sub.23
R.sub.24).sub.n O--, --C(O)NH(CH.sub.2 CH.sub.2 O).sub.n --,
##STR24## wherein R.sub.22-27 are independently selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.3-8 substituted alkyls,
C.sub.3-8 substituted cycloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy;
R.sub.28 is selected from the group consisting of hydrogen,
C.sub.1-6 alkyls, C.sub.3-12 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cycloalkyls, aryls substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy, NO.sub.2, haloalkyl and
halogen; and n and q are independently selected positive
integers.
25. The compound of claim 1, wherein L.sub.2 is selected from the
group consisting of: (CH.sub.2).sub.j (CH.sub.2 CH.sub.2 O).sub.2
(CH.sub.2).sub.2 NH, --NH(CH.sub.2 CH.sub.2 O).sub.j
(CH.sub.2).sub.k NR.sub.29 --, --NH(CH.sub.2 CH.sub.2 O).sub.j --,
--NH(CR.sub.30 R.sub.31).sub.j O--, --C(O)(CR.sub.30
R.sub.31).sub.j NHC(O)(CR.sub.32 R.sub.33).sub.j NR.sub.29 --,
--C(O)O(CH.sub.2).sub.k O--, --C(O)(CR.sub.30 R.sub.31).sub.j
NR.sub.29 --, --C(O)NH(CH.sub.2 CH.sub.2 O).sub.j (CH.sub.2).sub.k
NR.sub.29 --, --C(O)O--(CH.sub.2 CH.sub.2 O).sub.j NR.sub.29 --,
--C(O)NH(CR.sub.30 R.sub.31).sub.j O--, --C(O)O(CR.sub.30
R.sub.31).sub.j O--, --C(O)NH(CH.sub.2 CH.sub.2 O).sub.j --,
##STR25## wherein R.sub.29-33 are independently selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted alkyls,
C.sub.3-8 substituted cycloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy;
R.sub.34 is selected from the group consisting of hydrogen,
C.sub.1-6 alkyls, C.sub.3-12 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cycloalkyls, aryls substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy, NO.sub.2, haloalkyl and
halogen; and j and k are independently selected positive
integers.
26. A compound of claim 1, selected from the group consisting of
##STR26##
27. A compound of claim 1, selected from the group consisting of
##STR27##
28. A method of preparing a camptothecin analog, comprising: a)
reacting a camptothecin derivative of the formula: ##STR28##
wherein: R.sub.1 is selected from the group consisting of amino
acid residues, peptide residues containing form about 2 to about 10
amino acids, Y.sub.3 --(L.sub.2).sub.p --A.sub.2 and R.sub.2 ;
Y.sub.3 is O, S or NR.sub.3 ; p is zero or one; L.sub.2 is a
bifunctional linker; A.sub.2 is selected from the group consisting
of hydrogen, amino protecting groups, NR.sub.8 R.sub.9, amino acid
residues, peptide residues containing from about 2 to about 10
amino acids, polymeric residues, R.sub.10, SR.sub.11, NC(O)R.sub.12
; D.sub.3 -D.sub.7 are independently selected from the group
consisting of H, C.sub.1-8 straight or branched alkyls, substituted
C.sub.1-8 straight or branched alkyls, aryls, substituted aryls,
arylalkyls, substituted aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8
alkoxys, C.sub.1-8 hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys,
gycals, CO.sub.2 R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl,
amino, SR.sub.15, NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4
and D5 optionally, when taken together, form a saturated 3-7
membered heterocyclic ring which may contain O, S or NR.sub.19
groups, where R.sub.19 is hydrogen or a C.sub.1-6 alkyl; D.sub.8
-D.sub.9 are independently selected from the group consisting of H,
C.sub.1-8 straight or branched alkyls, substituted C.sub.1-8
straight or branched alkyls, aryls, substituted aryls, arylalkyls,
substituted aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8
hydroxyalkyls; D.sub.10 is H, and R.sub.2-18 are independently
selected from the group consisting of hydrogen, C.sub.1-6 alkyls,
C.sub.3-19 branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6
substituted alkyls, C.sub.3-8 substituted cyloalkyls, aryls,
substituted aryls, aralkyls, C.sub.1-6 heteroalkyls, substituted
C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6
heteroalkoxy; with a blocked bifunctional spacer to form a
protected intermediate, and b) deprotecting said protected
intermediate and reacting the resultant deprotected intermediate
with an activated polymer under conditions sufficient to cause a
polymeric conjugate to be formed.
29. A method of preparing a polymer conjugate, comprising a)
reacting a compound of the formula ##STR29## wherein: D.sub.3
-D.sub.7 are independently selected from the group consisting of H,
C.sub.1-8 straight or branched alkyls, substituted C.sub.1-8
straight or branched alkyls, aryls, substituted aryls, arylalkyls,
substituted aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8 alkoxys,
C.sub.1-8 hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys, gycals,
CO.sub.2 R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl amino,
SR.sub.15, NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4 and
D.sub.5 optionally, when taken together, form a saturated 3-7
membered heterocyclic ring which may contain O, S or NR.sub.19
groups, where R.sub.19 is hydrogen or a C.sub.1-6 alkyl; D.sub.8
-D.sub.9 are independently selected from the group consisting of H,
C.sub.1-8 straight or branched alkyls, substituted C.sub.1-8
straight or branched alkyls, aryls, substituted aryls, arylalkyls,
substituted aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8
hydroxyalkyls; D.sub.10 is H, and R.sub.8-18 are independently
selected from the group consisting of hydrogen, C.sub.1-6 alkyls,
C.sub.3-19 branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6
substituted alkyls, C.sub.1-6 substituted cyloalkyls, aryls,
substituted aryls, aralkyls, C.sub.1-6 heteroalkyls, substituted
C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6
heteroalkoxy; with a blocked bifunctional spacer in an inert
solvent under conditions sufficient to open the E lactone and form
a protected intermediate of formula (VI) ##STR30## wherein R.sub.35
is a residue of a blocked bifunctional spacer; b) acylating the
C.sub.17 OH of said blocked intermediate; and c) deblocking said
blocked intermediate and reacting at least about 2 equivalents of
the resultant deblocked intermediate with an activated polymer
under conditions sufficient to cause a polymeric conjugate to be
formed.
30. A method of treating a topoisomerase I inhibitor-related
disease in mammals, comprising administering an effective amount of
a compound of claim 1 to a mammal in need of such treatment.
Description
TECHNICAL FIELD
The present invention relates to polymeric derivatives of
camptothecin and related topoisomerase inhibitor compounds. More
particularly, the invention relates to camptothecin derivatives in
which the E ring lactone has been modified to allow attachment of
substantially non-antigenic polymers.
BACKGROUND OF THE INVENTION
Camptothecin is a water-insoluble cytotoxic alkaloid produced by
Camptotheca accuminiata trees indigenous to China and Nothapodytes
foetida trees indigenous to India. Camptothecin and related analogs
are known to be potential anticancer agents and have demonstrated
therapeutic activity in vitro and in vivo.
Over the years, various proposals have been made to increase the
water solubility and/or therapeutic and pharmacokinetic properties
of camptothecin analogs. One early attempt to increase the water
solubility of camptothecin is disclosed in U.S. Pat. No. 4,943,579
(hereinafter the '579 patent). The '579 patent discloses certain
simple 20(S)-camptothecin amino acid esters in their salt forms as
water soluble prodrugs. As evidenced by the data provided in Table
2 of the '579 patent, hydrolysis is rapid. Consequently, at
physiologic pH, the insoluble base is rapidly generated after
injection, binds to proteins and is quickly eliminated from the
body before full therapeutic effect can be achieved. A related
effort was directed to developing a water-soluble camptothecin
sodium salt. Unfortunately, the water-soluble sodium salt of
camptothecin remained too toxic for clinical application (Gottlieb
et al,. 1970 Cancer Chemotlier, Rep. 54, 461; Moertel et al,. 1972
ibid, 56, 95; Gottlieb et al., 1972 ibid, 56, 103).
Other attempts at improving the solubility of camptothecin analogs
are provided by Greenwald et al. For example, commonly-assigned
U.S. Pat. No. 5,965,566 discloses camptothecin attached to a
bifunctional PEG using an amino acid-based linkers. U.S. Pat. No.
6,011,042 discloses polymeric derivatives of
10-hydroxycamptothecin. The PEG-derivatives provide the artisan
with a water soluble prodrug which, upon administration, eventually
liberate the parent compound in vivo. Prodrugs allow the artisan to
modify the onset and/or duration of action of an agent in vivo and
can modify the transportation, distribution or solubility of a drug
in the body. Furthermore, prodrug formulations often reduce the
toxicity and/or otherwise overcome difficulties encountered when
administering pharmaceutical preparations.
The E-lactone ring is thought to be essential for anti-cancer
activity. Nonetheless, Sawada et al. have suggested in U.S. Pat.
No. 4,914,205 and Chem. Pharm. Bull. 41(2) 310-313 (1993) prodrugs
of camptothecin and the 7-ethyl derivative thereof having a
modified E-lactone-ring. Specifically, the E-lactone ring is opened
to provide 17-O-acyl derivatives and the authors demonstrated
improved solubility of HCl salts thereof when compared to the
native alkaloid. In spite of the increases in solubility
demonstrated by the open lactone E-ring derivatives, further
improvements have been sought. For example, after administration,
the prodrug must be converted back into its active form in order to
have biological (anticancer) activity. Consequently, these
derivatives are highly dependent upon the hydrolysis of the
respective hydroxy-acids to free the 17-hydroxyl group in order to
regenerate the E-ring lactone. Such conversions, however, are
difficult to predict. It would be highly desirable to provide
E-lactone ring modified camptothecin analogs with extended
circulating half lives and more predictable rates of regenerating
the closed lactone ring. The present invention addresses this
need.
SUMMARY OF THE INVENTION
In one aspect of the invention, compounds of Formula (I) are
provided: ##STR2##
wherein: R.sub.1 is selected from the group consisting of amino
acid residues, peptide residues containing from about 2 to about 10
amino acids, Y.sub.3 --(L.sub.2).sub.p --A.sub.2 and R.sub.2 ;
Y.sub.3 is O, S or NR.sub.3 ; p is zero or one; L.sub.2 is a
bifunctional linker; Y.sub.1 s O, S, or NR.sub.4 ; Y.sub.2 is O, S,
CR.sub.5 R.sub.6 or NR7; L.sub.1 is a bifunctional linker; a and b
are independently zero or one; A.sub.1 and A.sub.2 are
independently selected from the group consisting of hydrogen, amino
protecting groups, NR.sub.8 R.sub.9, amino acid residues, peptide
residues containing from about 2 to about 10 amino acids; polymeric
residues, R.sub.10, SR.sub.11, NC(O)R.sub.12 ; D.sub.3 -D.sub.7 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyls, substituted
aryalkyls, C.sub.1-8 allkylaryls, C.sub.1-8 alkoxys, C.sub.1-8
hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys, gycals, CO.sub.3
R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl, amino, SR.sub.15,
NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4 and D.sub.5
optionally, when taken together, form a saturated 3-7 membered
heterocyclic ring which may contain O, S or NR.sub.19 groups, where
R.sub.19 is hydrogen or a C.sub.1-6 alkyl; D.sub.8 -D.sub.9 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyls, substituted
aryalkyls, C.sub.1-8 allkylaryls and C.sub.1-8 hydroxy alkyls; and
R.sub.2-18 are independently selected from the group consisting of
hydrogen, C.sub.1-6 alkyls, C.sub.3-19 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cycloalkyls, aryls, substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy; except that at least one of
A.sub.1 and A.sub.2 comprise a polymeric residue.
In another aspect of the invention there is provided bifunctional
compounds that are formed when at least one of A.sub.1 and A.sub.2
comprises a polymeric residue and the polymeric residue is
functionalized on both the alpha and omega termini to allow two
equivalents of the camptothecin to be delivered per equivalent of
the polymer which is preferably PEG. Such preferred compositions
correspond to formulae (IIIa) and IIIb) below: ##STR3##
wherein all variables are as previously defined above.
For purposes of the present invention, the term "residue" shall be
understood to mean that portion of a camptothecin derivative or
bifunctional spacer which remains after it has undergone a
substitution reaction.
Methods of preparing the compositions of the invention and methods
of treatment using the same are also provided.
For purposes of the present invention, the term "polymeric residue"
or "PEG residue" shall each be understood to mean that portion of
the polymer or PEG which remains after it has undergone a reaction
with a heteroaromatic amine-containing compound.
For purposes of the present invention, the term "alkyl" shall be
understood to include straight, branched, substituted, e.g. halo-,
alkoxy-, nitro-, C.sub.1-12 alkyls, C.sub.3-8 cycloalkyls or
substituted cycloalkyls, etc.
For purposes of the present invention, the term "substituted" shall
be understood to include adding or replacing one or more atoms
contained within a functional group or compound with one or more
different atoms.
For purposes of the present invention, substituted alkyls include
carboxyalkyls, aminoalkyls, dialkylaminos, hydroxyalkyls and
mercaptoalkyls; substituted alkenyls include carboxyalkenyls,
aminoalkenyls, dialkenylaminos, hydroxyalkenyls and
mercaptoalkenyls; substituted alkynyls include carboxyalkynyls,
aminoalkynyls, dialkynylaminos, hydroxyalkynyls and
mercaptoalkynyls; substituted cycloalkyls include moieties such as
4-chlorocyclohexyl; aryls include moieties such as napthyl;
substituted aryls include moieties such as 3-bromo-phenyl; aralkyls
include moieties such as toluyl; heteroalkyls include moieties such
as ethylthiophene; substituted heteroalkyls include moieties such
as 3-methoxy-thiophene; alkoxy includes moieties such as methoxy;
and phenoxy includes moieties such as 3-nitrophenoxy. Halo- shall
be understood to include fluoro, chloro, iodo and bromo.
The term "sufficient amounts" for purposes of the present invention
shall mean an amount which achieves a therapeutic effect as such
effect is understood by those of ordinary skill in the art.
One advantage of the invention is that the artisan is provided with
prodrugs of camptothecin derivatives with improved aqueous
solubility.
Another advantage of the compounds of the invention is that in
certain preferred embodiments, the releasble polymer not only
extends the circulating life of the camptothecin derivative, but it
also provides a means for controlling conversion of the open E-ring
lactone back to the biologically active form. This result is
achieved by virtue of the fact that the open E-ring camptothecin
derivative cannot hydrolyze into the closed E lactone ring until
the polymer is released.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-6 schematically illustrate methods of forming compounds of
the present invention which are described in the Examples.
DETAILED DESCRIPTION OF THE INVENTION
A. Formula (I)
In one preferred embodiment of the invention, there are provided
compounds of the Formula (I): ##STR4##
wherein: R.sub.1 is selected from the group consisting of amino
acid residues, peptide residues containing from about 2 to about 10
amino acids, Y.sub.3 --(L.sub.2).sub.p --A.sub.2 and R.sub.2 ;
Y.sub.3 is O, S or NR.sub.3 ; p is zero or one; L.sub.2 is a
bifunctional linker; Y.sub.1 is O, S or NR4; Y.sub.2 is O, S,
CR.sub.5 R.sub.6 or NR.sub.7 ; L.sub.1 is a bifunctional linker; a
and b are independently zero or one; A.sub.1 and A.sub.2 are
independently selected from the group consisting of hydrogen, amino
protecting groups, NR.sub.8 R.sub.9, amino acid residues, peptide
residues containing from about 2 to about 10 amino acids; polymeric
residues, R.sub.10, SR.sub.11, NC(O)R.sub.12 ; D.sub.3 -D7 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyl, substituted
aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8 alkoxys, C.sub.1-8
hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys, gycals, CO.sub.2
R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl, amino, SR.sub.15,
NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4 and D.sub.5
optionally, when taken together, form a saturated 3-7 membered
heterocyclic ring which may contain O, S or NR.sub.19 groups, where
R.sub.19 is hydrogen or a C.sub.1-6, alkyl, D.sub.8 -D.sub.9 are
independently selected from the group consisting of H, C.sub.1-8
straight or branched alkyls, substituted C.sub.1-8 straight or
branched alkyls, aryls, substituted aryls, arylalkyls, substituted
aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8 hydroxyalkyls; and
R.sub.2-18 are independently selected from the group consisting of
hydrogen, C.sub.1-6 alkyls, C.sub.3-19 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cyloalkyls, aryls, substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy; except that at least one of
A.sub.1 and A.sub.2 comprise a polymeric residue.
In many preferred aspects of the invention, one of A.sub.1 and
A.sub.2 includes a polymer residue. The polymer residue optionally
includes a capping group designated J herein. Within this aspect of
the invention, when A.sub.1 is a polymer residue, the capping group
J is selected from among, for example, OH, NH.sub.2, SH, CO.sub.2
H, C.sub.1-6 alkyl moieties and ##STR5##
Alternatively, when R.sub.1 is Y.sub.3 --(L.sub.2).sub.p --A.sub.2
in formula (I), and A.sub.2 is a polymer residue, the capping group
J is selected from among, for example, OH, NH.sub.2, SH--, CO.sub.2
H, C.sub.1-6 alkyl moieties and ##STR6##
The preferred capping groups allow preferred compositions of (IIIa)
and (IIIb), respectively, ##STR7##
to be formed, wherein all variables are as previously defined.
When L.sub.1 and/or L.sub.2 include an amino acid residue, the
amino acid can be selected from any of the known
naturally-occurring L-amino acids is, e.g., alanine, valine,
leucine, isoleucine, glycine, serine, threonine, methionine,
cysteine, phenylalanine, tyrosine, tryptophan, aspartic acid,
glutamic acid, lysine, arginine, histidine, proline, and/or a
combination thereof, to name but a few. When L.sub.1 and/or L.sub.2
include a peptide, the peptide ranges in size, for instance, from
about 2 to about 10 amino acid residues. In one preferred
embodiment, the peptide is Gly-Phe-Leu-. Alternatively, glycine can
be added to the aforementioned trippeptide after leucine to form a
4 residue peptide.
The amino acid residues are preferably of the formula ##STR8##
wherein X' is O, S or NR.sub.34, Y.sub.4 is O , S or NR.sub.35, and
f is a positive integer from about 1 to about 10, preferably 1; and
R.sub.34 and R.sub.35 are independently selected from the same
group as that which defines R.sub.31 but each is preferably H or
lower alkyl.
Derivatives and analogs of the naturally occurring amino acids, as
well as various art-known non-naturally occurring amino acids (D or
L), hydrophobic or non-hydrophobic, are also contemplated to be
within the scope of the invention. Simply by way of example, amino
acid analogs and derivates include: 2-aminoadipic acid,
3-amino-adipic acid, beta-alanine, beta-aminopropionic acid,
2-aminobutyrc acid, 4-amino-butyric acid, piperidinic acid,
6-aminocaproic acid, 2-aminoheptanoic acid, 2-aminoisobutyric acid,
3-aminoisobutyric acid, 2-aminopimelic acid, 2,4-diamino-butyric
acid, desmosine, 2,2-diaminopimelic acid, 2,3-diaminopropionic
acid, n-ethylglycine, N-ethylasparagine, 3-hydroxyproline,
4-hydroxyproline, isodesmo-sine, allo-isoleucine, N-methylglycine,
sarcosine, N-methylisoleucine, 6-N-methyl-lysine, N-methylvaline,
norvaline, norleucine, ornithine, and others too numerous to
mention, that are listed in 63 Fed. Reg., 29620, 29622,
incorporated by reference herein.
Short peptides are, for example, peptides ranging from 2 to about
10, or more, amino acid residues, as mentioned supra.
Within most aspects of the invention, the following embodiments are
preferred: Y.sub.2 and Y.sub.2 are each oxygen, R.sub.2 -R.sub.14
and D.sub.3 -D.sub.10 are each hydrogen, L.sub.1 is selected from
among (CH.sub.2).sub.n, (CH.sub.2).sub.3 NH--C(O) (CH.sub.2).sub.3
NH-- --NH(CH.sub.2 CH.sub.2 O).sub.n (CH.sub.2).sub.n NR.sub.22 --,
--NH(CH.sub.2 CH.sub.2 O).sub.n --, --NH(C.sub.23 R.sub.24).sub.n
O--, --C(O)(CR.sub.23 R.sub.24).sub.n NHC(O)(CR.sub.25
R.sub.26).sub.q NR.sub.27 --, --C(O)O(CH.sub.2).sub.n O--,
--C(O)(CR.sub.23 R.sub.24).sub.n NR.sub.27 --, --C(O)NH(CH.sub.2
CH.sub.2 O).sub.n (CH.sub.2).sub.n NR.sub.27 --, --C(O)O--(CH.sub.2
CH.sub.2 O).sub.n NR.sub.27 --, --C(O)NH(CR.sub.23 R.sub.24).sub.n
O--, --C(O)O(CR.sub.23 R.sub.24).sub.n O--, --C(O)NH(CH.sub.2
CH.sub.2 O).sub.n --, ##STR9## wherein R.sub.22-27 are
independently selected from the group consisting of hydrogen,
C.sub.1-6 alkyls, C.sub.3-12 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cycloalkyls, aryls substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy; R.sub.28 is selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted alkyls,
C.sub.3-8 substituted cycloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy,
NO.sub.2, haloalkyl and halogen; and n and q are independently
selected positive integers.
L.sub.2 is preferably selected from among: (CH.sub.2).sub.j
(CH.sub.2 CH.sub.2 O).sub.2 (CH.sub.2).sub.2 NH, --NH(CH.sub.2
CH.sub.2 O).sub.j (CH.sub.2).sub.k NR.sub.29 --, --NH(CH.sub.2
CH.sub.2 O).sub.j --, --NH(CR.sub.30 R.sub.31).sub.j O--,
--C(O)(CR.sub.30 R.sub.31).sub.j NHC(O)(CR.sub.32 R.sub.33).sub.j
NR.sub.29 --, --C(O)O(CH.sub.2).sub.k O--, --C(O)(CR.sub.30
R.sub.31).sub.j NR.sub.29 --, --C(O)NH(CH.sub.2 CH.sub.2 O).sub.j
(CH.sub.2).sub.k NR.sub.29 --, --C(O)O--(CH.sub.2 CH.sub.2 O).sub.j
NR.sub.29 --, --C(O)NH(CR.sub.30 R.sub.31).sub.j O--,
--C(O)O(CR.sub.30 R.sub.31).sub.j O--, --C(O)NH(CH.sub.2 CH.sub.2
O).sub.j --, ##STR10## wherein R.sub.29-33 are independently
selected from the group consisting of hydrogen, C.sub.1-6 alkyls,
C.sub.3-12 branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6
substituted alkyls, C.sub.3-8 substituted cycloalkyls, aryls
substituted aryls, aralkyls, C.sub.1-6 heteroalkyls, substituted
C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6
heteroalkoxy; R.sub.34 is selected from the group consisting of
hydrogen, C.sub.1-6 alkyls, C.sub.3-12 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls, C.sub.3-8 substituted
cycloalkyls, aryls substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy, NO.sub.2, haloalkyl and
halogen; and j and k are independently selected positive
integers.
B. Substantially Non-Antigenic Polymers
As stated above, A.sub.1 and A.sub.2 can comprise polymer residues.
The polymer residues are preferably water soluble and substantially
non-antigenic. Particularly preferred polymers useful in the
compositions of the present invention include polyalkylene oxides
such as polyethylene glycol. The polymer residues optionally the
previously mentioned capping groups, designated J, which allows a
bifunctional or bis-polymer system to be formed.
In those aspects of the invention where A.sub.1 includes the
polyethylene glycol residue, the PEG derivatives can be selected
from the following non-limiting list: --J--O--(CH.sub.2 CH.sub.2
O).sub.x --, J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2
NR.sub.20 --, J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2
SH--, --O--C(O)CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, --NR.sub.20 CH.sub.2 CH.sub.2 --O--(CH.sub.2 CH.sub.2
O).sub.x --CH.sub.2 CH.sub.2 NR.sub.20 --, and --SHCH.sub.2
CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
wherein: x is the degree of polymerization; R.sub.20 is selected
from the group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-12
branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted
alkyls, C.sub.3-8 substituted cyloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy
and J is a capping group.
Similarly, in those aspects of the invention where A.sub.2 includes
the polyethylene glycol residue, the PEG derivatives can be
selected from the following non-limiting list: of J--O--(CH.sub.2
CH.sub.2 O).sub.x,-- J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2
NR.sub.21 --, J--O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2
SH--, --O--C(O)CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2
C(O)--O--, --NR.sub.21 CH.sub.2 CH.sub.2 --O--(CH.sub.2 CH.sub.2
O).sub.x --CH.sub.2 CH.sub.2 NR.sub.21 --, and --SHCH.sub.2
CH.sub.2 --O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 CH.sub.2 SH--,
wherein: x is the degree of polymerization; R.sub.21 is selected
from the group consisting of hydrogen, C.sub.1 alkyls, C.sub.3-12
branched alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted
alkyls, C.sub.3-8 substituted cyloalkyls, aryls substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy
and J is a capping group.
For the purpose of the present invention the structure:
wherein x is a positive integer, is referred to as PEG throughout
the application.
The degree of polymerization for the polymer (x) can be from about
10 to about 2,300. This represents the number of repeating units in
the polymer chain and is dependent on the molecular weight of the
polymer. In certain preferred aspects, the amount of polymerization
is preferably sufficient to provide the polymer with a molecular
weight of at least about 20,000 daltons. Since the ethylene glycol
monomer has a molecular weight of 44, (x) is preferably at least
about 454. The (J) moiety is a capping group as defined herein,
i.e. a group which is found on the terminal of the polymer and, in
some aspects, can be selected from any of NH.sub.2, OH, SH--,
CO.sub.2 H, C.sub.1-6 alkyls or other PEG terminal activating
groups, as such groups are understood by those of ordinary
skill.
Also useful are polypropylene glycols, branched PEG derivatives
such as those described in commonly-assigned U.S. Pat. No.
5,643,575, "star-PEG's" and multi-armed PEG's such as those
described in Shearwater Corporation's 2001 catalog "Polyethylene
Glycol and Derivatives for Biomedical Application". The disclosure
of each of the foregoing is incorporated herein by reference. It
will be understood that the water-soluble polymer can be
functionalized for attachment to the bifunctional linkage groups if
required without undue experimentation.
In many aspects of the present invention, bis-activated
polyethylene glycols are preferred when di- or multi-substituted
polymer conjugates are desired. Alternatively, polyethylene glycols
(PEG's), mono-activated, C.sub.1-4 alkyl-terminated polyalkylene
oxides (PAO's) such as mono-methyl-terminated polyethylene glycols
(mPEG's) are preferred when mono-substituted polymers are
desired.
In order to provide the desired hydrolyzable linkage, mono- or
di-acid activated polymers such as PEG acids or PEG diacids can be
used as well as mono- or di-PEG amines and mono- or di-PEG diols.
Suitable PAO acids can be synthesized by first converting CH.sub.3
O-PEG-OH (mPEG-OH) to an ethyl ester followed by saponification.
See also Gehrhardt, H., et al. Polymer Bulletin 18: 487 (1987) and
Veronese, F. M., et al., J. Controlled Release 10; 145 (1989).
Alternatively, the PAO-acid can be synthesized by converting
mPEG-OH into a t-butyl ester followed by acid cleavage. See, for
example, commonly assigned U.S. Pat. No. 5,605,976. The disclosures
of each of the foregoing are incorporated by reference herein.
Although PAO's and PEG's can vary substantially in average
molecular weight, the polymer portion of the prodrug is at least
about 20,000 Da average in most aspects of the invention.
Preferably, the polymer portion of the compositions has a weight
average molecular weight of from about 20,000 Da to about 100,000
Da and more preferably from about 25,000 Da to about 60,000 Da. The
average molecular weight of the polymer selected for inclusion in
the prodrug must be sufficient so as to provide sufficient
circulation of the prodrug before hydrolysis of the linker.
The polymeric substances included herein are preferably
water-soluble at room temperature. A non-limiting list of such
polymers include polyalkylene oxide homopolymers such as
polyethylene glycol (PEG) or polypropylene glycols,
polyoxyethylenated polyols, copolymers thereof and block copolymers
thereof, provided that the water solubility of the block copolymers
is maintained.
In a further embodiment, and as an alternative to PAO-based
polymers, A.sub.1 and A.sub.2 can optionally comprise one or more
other effectively non-antigenic materials such as dextran,
polyvinyl alcohols, carbohydrate-based polymers,
hydroxypropylmethacrylamide (HPMA), polyalkylene oxides, and/or
copolymers thereof. See also commonly-assigned U.S. Pat. No.
6,153,655, the contents of which are incorporated herein by
reference. It will be understood by those of ordinary skill that
the same type of activation is employed as described herein as for
PAO's such as PEG. Those of ordinary skill in the art will further
realize that the foregoing list is merely illustrative and that all
polymeric materials having the qualities described herein are
contemplated. For purposes of the present invention, "effectively
non-antigenic" and "substantially non-antigenic" shall be
understood to include all polymeric materials understood in the art
as being substantially non-toxic and not eliciting an appreciable
immune response in mammals.
It will be clear from the foregoing that other polyalkylene oxide
derivatives of the foregoing, such as the polypropylene glycol
acids, etc., as well as other bifunctional linking groups are also
contemplated.
C. Camptothecin and Camptothecin Analogs
Camptothecin and certain related analogues and derivatives share
the structure: ##STR11##
From this core structure, various derivatives are known. For
example, the A ring in either or both of the 10- and 11-positions
can be substituted with an OH. The A ring can also be substituted
in the 9-position with a straight or branched C.sub.1-30 alkyl or
C.sub.1-7 alkoxy, optionally linked to the ring by a heteroatom
i.e. O or S. The B ring can be substituted in the 7-position with a
straight or branched C.sub.1-30 alkyl or substituted alkyl-,
C.sub.5-8 cycloalkyl, C.sub.1-30 alkoxy, phenyl alkyl, etc., alkyl
carbamate, alkyl carbazides, phenyl hydrazine derivatives, amino,
aminoalkyl, aralkyl, etc. Other substitutions are possible in the
C, D and E rings. See, for example, U.S. Pat. Nos. 5,004,758,
4,943,579, Re 32,518, 4,894,456, 5,225, 5,053,512, 4,981,968,
5,049,668, 5,106,742, 5,180,722, 5,244,903, 5,227,380, 5,122,606,
5,122,526, and 5,340,817, the contents of each of which are
incorporated herein by reference.
In most aspects of the invention, the camptothecin derivatives
which are employed in the formation of the compositions of the
present invention are generally of the formula ##STR12##
wherein:
D.sub.3 -D.sub.7 are independently selected from the group
consisting of H, C.sub.1-8 straight or branched alkyls, substituted
C.sub.1-8 straight or branched alkyls, aryls, substituted aryls,
arylalkyls, substituted aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8
alkoxys, C.sub.1-8 hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys,
gycals, CO.sub.2 R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl,
amino, SR.sub.15, NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4
and D.sub.5 optionally, when taken together, form a saturated 3-7
membered heterocyclic ring which may contain O, S or NR.sub.19
groups, where R.sub.19 is hydrogen or a C.sub.1-6 alkyl; D.sub.8
-D.sub.9 are independently selected from the group consisting of H,
C.sub.1-8 straight or branched alkyls, substituted C.sub.1-8
straight or branched alkyls, aryls, substituted aryls, arylalkyls,
substituted aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8
hydroxyalkyls; and R.sub.8-18 are independently selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-19 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted alkyls,
C.sub.3-8 substituted cyloalkyls, aryls, substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6
heteroalkoxy.
In other preferred aspects of the invention, the following can be
used: ##STR13##
Still further camptothecin analogs which can be used in the
practice of the present invention include, 10,11-oxycamptothecin,
10,11-methylene dioxycamptothecin, 7-ethylcamptothecin,
9-amino-camptothecin, to name but a few.
Those of ordinary skill will realize that the foregoing is merely
illustrative of the camptothecin derivatives useful in practicing
the present invention. The only limitations on the camptothecin
derivatives useful in the invention is that the specific derivative
must be capable of undergoing the opening of the E-lactone ring,
allowing a polymer to be attached thereto and, after
administration, allowing hydrolysis to occur which allows the
E-lactone ring to be re-formed in vivo.
D. Synthesis of the Camptothecin-polymeric Prodrugs
Synthesis of specific representative polymer prodrugs is set forth
in the Examples. Generally, however, in one preferred method of
preparing the prodrug transport systems of the present invention,
the E-lactone ring is opened, a capped bifunctional linker is
attached at the 17-position of the open lactone ring, the blocking
group is removed and followed by PEGylation with appropriate
solvent and coupling agent, if required. The lactone ring can be
opened using known techniques such as by dissolving the
camptothecin derivative in N,N-dimethylethylenediamine (2 in the
examples) or in isopropylamine (9 in the examples) or other
suitable reagent solvents containing a primary amine and heating
the reaction solution for a sufficient amount of time to allow the
ring to be opened.
Once the E ring has been opened, the artisan is provided with a
camptothecin derivative of the formula: ##STR14##
wherein: R.sub.1 is selected from the group consisting of amino
acid residues, peptide residues containing from about 2 to about 10
amino acids, Y.sub.3 --(L.sub.2).sub.p --A.sub.2 and R.sub.2 ;
Y.sub.3 is O, S or NR.sub.3 ; p is zero or one; L.sub.2 is a
bifunctional linker; A.sub.2 is selected from the group consisting
of hydrogen, amino protecting groups, NR.sub.8 R.sub.9, amino acid
residues, peptide residues containing from about 2 to about 10
amino acids; polymeric residues, R.sub.10, SCR.sub.11,
NC(O)R.sub.12 ; D.sub.3 -D.sub.7 are independently selected from
the group consisting of H, C.sub.1-8 straight or branched alkyls,
substituted C.sub.1-8 straight or branched alkyls, aryls,
substituted aryls, arylalkyls, substituted aryalkyls, C.sub.1-8
alkylaryls, C.sub.1-8 alkoxys, C.sub.1-8 hydoxy-alkyls, C.sub.1-8
aminoalkoxy, aryloxys, gycals, CO.sub.2 R.sub.13, R.sub.14, nitro,
cyano, halo, hydroxyl, amino, SR.sub.15, NR.sub.16 R.sub.17 or
OR.sub.18, where D.sub.4 and D.sub.5 optionally, when taken
together, form a saturated 3-7 membered heterocyclic ring which may
contain O, S or NR.sub.19 groups, where R.sub.19 is hydrogen or a
C.sub.1-6 alkyl; D.sub.8 -D.sub.9 are independently selected from
the group consisting of H, C.sub.1-8 straight or branched alkyls,
substituted C.sub.1-8 straight or branched alkyls, aryls,
substituted aryls, arylalkyls, substituted aryalkyls, C.sub.1-8
alkylaryls and C.sub.1-8 hydroxyalkyls; and R.sub.2-18 are
independently selected from the group consisting of hydrogen,
C.sub.1-6 alkyls, C.sub.3-19 branched alkyls, C.sub.3-8
cycloalkyls, C.sub.1-6 substituted alkyls,C.sub.3-8 substituted
cyloalkyls, aryls, substituted aryls, aralkyls, C.sub.1-6
heteroalkyls, substituted C.sub.1-6 heteroalkyls, C.sub.1-6 alkoxy,
phenoxy and C.sub.1-6 heteroalkoxy; which is then reacted with a
blocked bifunctional spacer to form a protected intermediate. This
intermediate is then deblocked and reacted with an activated
polymer under conditions sufficient to cause a polymeric conjugate
to be formed.
A non-limiting list of activated polymers include bis-succinimidyl
carbonate activated PEG (SC-PEG), bis-thiazolidine-2-thione
activated PEG (T-PEG), N-hydroxyphthalamidyl carbonate activated
PEG (BSC-PEG), see commonly assigned U.S. Ser. No. 09/823,296, the
disclosure of which is incorporated herein by reference,
succinimidyl succinate activated PEG (SS-PEG), imidazole-activated
PEG (PGG-IMD), bis-carboxylic acid- PEG (PEG-CO.sub.2 H) and
mono-activated PEG's such as those found in, for example, in the
aforementioned 2001 Shearwater Catalog.
Conjugation of the intermediate to the PEG residue can be carried
out in the presence of a coupling agent. A non-limiting list of
suitable coupling agents include 1,3-diisopropylcarbodiimide
(DIPC), any suitable dialkyl carbodiimide,
2-halo-1-alkyl-pyridinium halides (Mukaiyama reagents),
1-(3-dimethylaminopropyl)-3-ethyl carbodiimide (EDC), propane
phosphonic acid cyclic anhydride (PPACA) and phenyl
dichlorophosphates, etc. which are available, for example from
commercial sources such as Sigma-Aldrich Chemical, or synthesized
using known techniques.
Preferably the substituents are reacted in an inert solvent such as
tetrahydrofuran (TBF), acetonitrile (CH.sub.3 CN), methylene
chloride (DCM), chloroform (CHCl.sub.3), dimethylformamide (DMF) or
mixtures thereof. The reaction is preferably conducted in the
presence of a base, such as dimethylaminopyridine (DMAP),
diisopropyl ethylamine, pyridine, triethylamine, KOH, potassium
t-butoxide and NaOH, etc. and at a temperature from 0 .degree. C.
up to about 22.degree. C. (room temperature).
In an alternative embodiment, the compositions of the present
invention are prepared by using the blocked bifunctional spacer to
open the E-lactone ring in an inert solvent, acylating the
17-position OH group with, for example acetic or butyric anhydride,
deblocking the bifunctional spacer and attaching the polymer.
Specifically, the reaction involves reacting a compound of the
formula ##STR15##
wherein: D.sub.3 -D.sub.7 are independently selected from the group
consisting of H, C.sub.1-8 straight or branched alkyls, substituted
C.sub.1-8 straight or branched alkyls, aryls, substituted aryls,
arylalkyls, substituted aryalkyls, C.sub.1-8 alkylaryls, C.sub.1-8
alkoxys, C.sub.1-8 hydroxy-alkyls, C.sub.1-8 aminoalkoxy, aryloxys,
gycals, CO.sub.2 R.sub.13, R.sub.14, nitro, cyano, halo, hydroxyl,
amino, SR.sub.15,NR.sub.16 R.sub.17 or OR.sub.18, where D.sub.4 and
D.sub.5 optionally, when taken together, form a saturated 3-7
membered heterocyclic ring which may contain O, S or NR.sub.19
groups, where R.sub.19 is hydrogen or C.sub.1-6 alkyl; D.sub.8
-D.sub.9 are independently selected from the group consisting of H,
C.sub.1-8 straight or branched alkyls, substituted C.sub.1-8
straight or branched alkyls, aryls, substituted aryls, arylalkyls,
substituted aryalkyls, C.sub.1-8 alkylaryls and C.sub.1-8
hydroxyalkyls; and R.sub.8-18 are independently selected from the
group consisting of hydrogen, C.sub.1-6 alkyls, C.sub.3-19 branched
alkyls, C.sub.3-8 cycloalkyls, C.sub.1-6 substituted
alkyls,C.sub.3-8 substituted cyloalkyls, aryls, substituted aryls,
aralkyls, C.sub.1-6 heteroalkyls, substituted C.sub.1-6
heteroalkyls, C.sub.1-6 alkoxy, phenoxy and C.sub.1-6 heteroalkoxy;
with a blocked bifunctional spacer in an inert solvent under
conditions sufficient to open the E lactone and form a blocked
intermediate of formula (VI) ##STR16## wherein R.sub.35 is a
residue of a blocked bifunctional spacer; b) acylating the C.sub.17
hydroxyl of the blocked intermediate, and c) deprotecting the
blocked intermediate and reacting it with an activated polymer
under conditions sufficient to cause a polymeric conjugate to be
formed.
Regardless of the synthesis selected, some of the preferred
compounds which result from the synthetic techniques described
herein include: ##STR17##
where all variables are as previously defined and ##STR18##
where PEG=Me--O--(CH.sub.2 CH.sub.2 O).sub.x -- or --O--(CH.sub.2
CH.sub.2 O).sub.x --
E. Methods of Treatment
Another aspect of the present invention provides methods of
treatment for various medical conditions, including topoisomerase
inhibitor-related diseases in mammals. The methods include
administering to the mammal in need of such treatment, an effective
amount of a prodrug, of a camptothecin, camptothecin derivative,
camptothecin analog and/or a mixture thereof, such as,those
described herein. The compositions are useful for, among other
things, treating neoplastic disease, reducing tumor burden,
preventing metastasis of neoplasms and preventing recurrences of
tumor/neoplastic growths in mammals.
The amount of the inventive composition administered will depend
upon several factors, including potency of the parent molecule
included therein and specific disease being treated. Generally, the
amount of prodrug used in the treatment methods is that amount
which effectively achieves the desired therapeutic result in
mammals. Naturally, the dosages of the various prodrug compounds
will vary somewhat depending upon the parent compound, rate of in
vivo hydrolysis of the open E ring, the molecular weight of the
polymer used, if any, etc. In general, dosing is based upon the
amount of native (unmodified E-lactone ring) camptothecin or
derivative thereof. The camptothecin and derivatives of
camptothecin are generally administered in amounts ranging from
about 5 to about 500 mg/m.sup.2 per day. The range set forth above
is illustrative and those skilled in the art will determine the
optimal dosing of the prodrug selected based on clinical experience
and the treatment indication.
The compositions, including prodrugs, of the present invention can
be included in one or more suitable pharmaceutical compositions for
administration to mammals. The pharmaceutical compositions may be
in the form of a solution, suspension, tablet, capsule or the like,
prepared according to methods well known in the art. It is also
contemplated that administration of such compositions may be by the
oral, inhalation and/or parenteral routes depending upon the needs
of the artisan. A solution and/or suspension of the composition may
be utilized, for example, as a carrier vehicle for injection or
infiltration of the composition by any art known methods, e.g., by
intravenous, intramuscular, subdermal injection and the like. Such
administration may also be by infusion into a body space or cavity,
as well as by inhalation and/or intranasal routes. In preferred
aspects of the invention, however, the prodrugs are parenterally
administered to mammals in need thereof.
EXAMPLES
The following examples serve to provide further appreciation of the
invention but are not meant in any way to restrict the effective
scope of the invention. All compounds mentioned in the following
examples are numbered with reference to FIGS. 1-6.
General Procedures. All reactions were run under an atmosphere of
dry nitrogen or argon. Commercial reagents were used without
further purification. All PEG compounds were 40 kDa and were dried
under vacuum or by azeotropic distillation from toluene prior to
use. .sup.13 C NMR spectra were obtained at 75.46 MHz using a
Varian Mercurye.RTM. 300 NMR spectrometer and deuterated chloroform
as the solvent unless otherwise specified. Chemical shifts
(.delta.) are reported in parts per million (ppm) downfield from
tetramethylsilane (TMS). All PEG conjugated compounds were
dissolved in saline for injection prior to in vivo drug treatments
and were given as their camptothecin equivalents (absolute amount
of camptothecin given). HPLC method. The reaction mixtures and the
purity of intermediates and final products were monitored by a
Beckman Coulter System Gold.RTM. HPLC instrument employing a
ZOBAXO.RTM. 300 SB C-8 reversed phase column (150.times.4.6 mm) or
a Phenomenex Jupiter.RTM. 300A C18 reversed phase column
(150.times.4.6 mm) with a multiwavelength UV detector, using a
gradient of 30-90% of acetonitrile in 0.5% trifluoroacetic acid
(TFA) at a flow rate of 1 mL/min.
Example 1
Compound 5. Camptothecin (1) (1.44 g, 4.14 mmol) was dissolved in
N,N-dimethylethylenediamine (2) (15 mL) and the reaction solution
was heated at 50 .degree. C. for 2 hours. The solvent was removed
under reduced pressure and the resulting solid washed with ether to
give 3, which was suspended with dimethylaminopyridine (DMAP, 1.0
g, 8.88 mmol) and 4 (1.3 g, 4.44 mmol) in anhydrous methylene
chloride (DCM, 10 mL). The resulting reaction mixture was refluxed
for 4 hours and then stirred at room temperature for 12 hours,
washed with 0.1N HCl, dried with MgSO.sub.4, filtered, and solvent
evaporated under reduced pressure. The crude material was purified
on silica gel column to give 5 (0.080 g, 0.13 mmol, 3%). .sup.13 C
NMR (67.8 MHz, CDCl.sub.3) .delta. 167.26, 157.15, 155.77, 153.69,
152.18, 148.76, 146.33, 145.71, 131.14, 130.65, 129.56, 128.37,
128.10, 128.02, 120.10, 95.82, 79.14, 77.83, 77.20, 67.01, 66.50,
50.03, 36.97, 31.84, 29.01, 28.37, 25.59, 7.73.
Example 2
Compound 6. To a solution of 5 (0.080 g, 0.13 mmol) in DCM (1 mL)
cooled in an ice bath, trifluoroacetic acid (TFA, 1 mL) was added
drop-wise and stirred for 20 min. The solvents were then removed
under reduced pressure to give 6 (0.080 g, 0.13 mmol, .about.100%).
.sup.13 C NMR (67.8 MHz, CDCl.sub.3) .delta. 167.50, 157.01,
153.95, 146.42, 145.31, 143.81, 134.69, 132.80, 129.26, 129.08,
128.52, 126.56, 120.92, 98.92, 78.27, 77.21, 66.69, 65.27, 50.47,
37.15, 31.33, 26.55, 25.58, 7.53.
Example 3a
Compound 8a. A solution of 6 (0.080 g, 0.13 mmol), 7a (1.50 g,
0.037 mmol), and DMAP (0.031 g, 0.25 mmol) in DCM (8 mL) was
stirred at room temperature for 12 hours. The reaction mixture was
washed with 0.1NHCl (2.times.10 mL) and the organic layer
evaporated under reduced pressure. The solid residue was
crystallized from isopropyl alcohol (IPA, 30 mL) to yield 8a (1.2
g, 0.029 mmol, 79%). .sup.13 C NMR (67.8 MHz, CDCl.sub.3) .delta.
166.41, 156.36, 155.64, 152.92, 151.50, 148.01, 145.76, 144.89,
130.76, 129.90, 128.84, 127.95, 127.58, 127.29, 119.31, 94.90,
67.0-73.5 (PEG), 66.29, 65.78, 63.05, 49.46, 36.69, 31.12, 28.39,
7.14.
Example 3b
Compound 8b. The procedure of Example 3a is followed, except that
PEG-CO.sub.2 H 7b (1.5 g, 0.037 mmol) and 2 equivalents of EDC is
used in place of 7a to form an amide-linked PEG conjugate.
Example 4
Compound 11. 1 (1.44 g, 4.14 mmol) was dissolved in isopropylamine
9 (35 ml) and the solution refluxed for 1.5 hours. The solvent was
removed under reduced pressure and the resulting solid washed with
ether to give 10, which was suspended with DMAP (0.29 g, 2.36 mmol)
and 4 (0.36 g, 1.18 mmol) in anhydrous chloroform (2 mL). The
resulting reaction mixture was heated at 60.degree. C. for 1 hour,
washed with 0.1N HCl, dried (MgSO.sub.4), filtered, and the solvent
evaporated under reduced pressure. The crude material was purified
by column chromatography to give 11 (0.068 g, 0.11 mmol, 3%).
.sup.13 C NMR (67.8 MHz, CDCl.sub.3) .delta. 171.26, 161.43,
156.41, 155.92, 155.33, 152.09, 148.46, 144.57, 130.66, 130.22,
129.37, 128.37, 127.90, 127.71, 123.90, 100.57, 79.17, 77.20,
75.92, 65.22, 62.13, 50.27, 41.72, 37.09, 32.87, 29.33, 28.46,
22.74, 22.44, 7.90.
Example 5
Compound 12. To a solution of compound 11 (0.68 g, 0.11 mmol) in
DCM (1 mL), cooled in an ice bath, was added TFA (1 mL) drop-wise
and the solution stirred for 2 hours. The solvents were removed
under reduced pressure to give 12 (0.067 g, 0.11 mmol,
.about.100%). .sup.13 C NMR (67.8 MHz, CDCl.sub.3 /CD.sub.3 OD)
.delta. 171.74, 161.75, 157.19, 154.76, 152.01, 148.27, 144.55,
131.41, 130.62, 128.90, 128.58, 128.08, 127.91, 123.53, 101.24,
78.50, 64.99, 62.33, 50.23, 41.55, 37.06, 32.19, 26.35, 22.32,
22.00, 7.55.
Example 6a
Compound 13a. A solution of 12 (0.067 g, 0.11 mmol), 7a, (1.30 g,
0.032 mmol), and DMAP (0.027 g, 0.22 mmol) in DCM (8 mL) was
stirred at room temperature for 12 hours. The reaction mixture was
washed with 0.1N HCl (2.times.10 mL) and the organic layer
evaporated under reduced pressure. The solid residue was
crystallized from IPA (30 mL) to yield 13a (1.1 g, 0.028 mmol,
86%). .sup.13 C NMR (67.8 MHz, CDCl.sub.3) .delta. 170.64, 160.74,
155.82, 154.54, 151.65, 147.90, 144.02, 134.37, 130.35, 129.57,
128.77, 128.03, 127.43, 127.20, 99.61, 67.0-73.5 (PEG), 64.63,
63.23, 61.49, 49.71, 41.07, 37.02, 32.11, 28.74, 22.20, 21.84,
7.41.
Example 6b
Compound 13b. The procedure of Example 6a is followed, except that
PEG-CO.sub.2 H 7b (1.5 g, 0.037 mmol) is used with 2 equivalents of
EDC in place of 7a to form an amide-linked PEG conjugate.
Example 7
Compound 16. A mixture of 1 (0.34 g, 0.97 mmol), 14 (4.7 g, 19
mmol), and diisopropylethylamine (DIEA, 3.3 mL, 1.4 mmol) in
dimethylformamide (DMF, 7 mL) was heated at 70.degree. C. for 48
hours and a clear solution was obtained. The solvent was removed
under reduced pressure, and the resulting solid washed with hexane
and then ether to give 15 which was suspended in anhydrous DCM (10
mL) and cooled to 0.degree. C. in an ice bath. Acetic anhydride
(0.10 mL, 1.1 mmol) and DMAP (0.057 g, 0.47 mmol) were added to the
above suspension and stirred for 3 hours at ambient temperature.
The reaction mixture was washed with 0.1 N sodium bicarbonate (10
mL), and the organic layer evaporated under reduced pressure. The
residue was purified on silica gel column to give pure 16 (0.25 g,
0.39 mmol, 40%). .sup.13 C NMR (67.8 MHz, CDCl.sub.3) .delta.
172.19, 170.95, 161.38, 156.80, 155.91, 151.42, 148.04, 144.05,
130.42, 130.00, 128.92, 127.89, 127.68, 127.58, 127.26, 124.77,
100.60, 79.15, 78.55, 70.14, 69.37, 58.78, 50.23, 40.33, 39.04,
32.93, 28.40, 20.99, 7.92.
Example 8
Compound 17. To a solution of 16 (0.12 g, 0.19 mmol) in DCM (1 mL)
cooled in an ice bath was added TFA (1 mL) dropwise and stirred for
30 minutes. Solvent was removed under reduced pressure to give
6(0.12 g, 0.19 mmol, .about.100%). .sup.13 C NMR (67.8 MHz,
CDCl.sub.3) .delta. 173.01, 172.22, 161.33, 157.08, 149.97, 146.13,
142.92, 132.94, 131.47, 128.55, 128.40, 128.10, 127.67, 127.23,
125.13, 117.41, 113.59, 102.62, 78.65, 70.19, 69.37, 66.48, 58.63,
50.67, 40.06, 39.28, 32.68, 20.78, 7.62.
Example 9a
Compound 18a. A solution of 17 (0.050 g, 0.090 mmol), 7a (1.20 g,
0.030 mmol), and DMAP (0.022 g, 0.18 mmol) in DCM (6 mL) was
stirred at room temperature for 12 hours. The reaction mixture was
washed with 0.1N HCl (2.times.10 mL) and the organic layer
evaporated under reduced pressure. The solid residue was
crystallized from IPA (30 mL) to yield 18a (1.1 g, 0.027 mmol,
89%). .sup.13 C NMR (67.8 MHz, CDCl.sub.3) 6 171.82, 170.32,
160.71, 155.75, 155.23, 151.59, 147.82, 143.79, 134.41, 130.30,
129.55, 128.70, 127.90, 127.42, 127.11, 124.07, 99.59, 67.0-73.5
(PEG), 63.14, 58.50, 49.61, 40.17, 38.58, 32.14, 20.48, 7.38.
Example 9b
Compound 18b. The procedure of Example 9a is followed, except that
PEG-CO.sub.2 H 7b (1.5 g, 0.037 mmol) is used with 2 equivalents of
EDC in place of 7a to form an amide-linked PEG conjugate.
Example 10
The efficacy of open-form camptothecin analogs against a
subcutaneous human mammary carcinoma (MX-1) grown in nude mice was
determined as follows. Following at least one week of acclimation,
tumors were established by implanting small tumor fragments from
donor mice into a single subcutaneous site, on the left axillary
flank region of nude mice. The tumor implantation site was observed
twice weekly and measured once palpable. The tumor volume for each
mouse was determined by measuring two dimensions with calipers and
calculated using the formula: tumor
volume=(length.times.width.sup.2). When tumors reached the average
volume of approximately 75 mm.sup.3, the mice were divided into
their experimental groups, which consists of untreated controls,
PEG.sub.40,000 -ala-20(S)-Camptothecin, compound 8, and compound
18.
The mice were sorted to evenly distribute tumor size, grouped into
4 to 5 mice/cage, and ear punched for permanent identification.
Drugs were dosed intravenously via the tail vein as a single dose
(Qd1). Mouse weight and tumor sizes were measured at the beginning
of study and twice weekly through week 5. The overall growth of
tumors was calculated as the mean tumor volume at one week
following the end of the treatment. A percent treatment over
control (T/C) value was also calculated when the control group's
median tumor size reached approximately 800-1100 mm.sup.3 and again
at one week following treatment. The T/C value in percent is a
non-quantitative indication of anti-tumor effectiveness.
Treatments with PEG.sub.40,000 -ala-20(S)-Camptothecin, compounds 8
and 18 all caused significantly (P<0.05) smaller tumor volumes
as compared to control mice. In addition, at equivalent doses,
there was no significant (P<0.05) difference in the antitumor
activity of these three compounds.
TABLE 2 Efficacy Summary of PEG-Camptothecin Against a Human
Mammary Carcinoma (MX-1) Xenograft in Nude Mice.sup..alpha.
Treatment Tumor Volume T/C (%).sup..beta. Tumor Re- Schedule (mean
.+-. sem) At 1000 gression at Compound (mg/kg/dose) Day 21 mm.sup.3
Day 25 (#/grp) Control 0 2722 .+-. 223 -- 0/5 PEG.sub.40,000 - Qd1
(24) 15 .+-. 5 1.4 5/5 ala-20(S)- Campto. 8 Qd1 (24) 21 .+-. 6 3.0
5/5 18 Qd1 (24) 14 .+-. 2 2.5 4/4 .sup..alpha. Intravenous
treatment in nude mice bearing established tumors (.about.75
mm.sup.3). N = 4 to 5/group. .sup..beta. The median tumor volume of
treatment and control groups were measured and compared when the
control group's median tumor volume reached approximately 1000
mm.sup.3 and one week after final dosage (Day 15). T/C < 42% at
1000 mm.sup.3 is considered significant anti-tumor activity by the
Drug Evaluation Branch of the NCI.
While applicants are not bound by theory, it is believed that
significant conversion of the open lactone E ring into the closed
lactone ring has occurred in order to achieve the observed tumor
regression.
The various publications, patents, patent applications and
published applications mentioned in this application are hereby
incorporated by reference herein in their entireties.
While there have been described what are presently believed to be
the preferred embodiments of the invention, those skilled in the
art will realize that changes and modifications may be made without
departing from the spirit of the invention. It is intended to claim
all such changes and modifications as fall within the true scope of
the invention.
* * * * *